One of the things that people consider a downside of replacement hair is that the colour can fade, especially in the sun.
But, for people like you and me whose natural hair gets lighter in the summer anyway, this can be useful.
You can always 'help' the lightening along a bit by using a product like Sun-in, which is a spray and it lightens hair gradually as its exposed to heat (hairdryer) or sun.

Its usually recommended that glue is the best way to disguise the lace at the hairline, so you're right to consider a combination of tape for the back, sides and centre and using a glue along the first inch or so of the hairline.

For things like swimming and water activities, I've heard a lot of people recommend the blue backed tape tabs, or for normal wear, Stick-it tape.

When it comes to choosing a base, the more durable it is, the more detectable it is.
So the least detectable will be the Ultra Fine Swiss Lace or the normal Swiss Lace.
You have to decide when you're walking around on a daily basis wearing a system, if your priority will durability or detectability.
Personally, if I went for a more durable base and was having trouble with the hairline and worrying about it being noticeable, I'd find very little consolation in knowing that it was going to last me along time.
You could also consider combining laces and have a French Lace at the back with a Swiss Lace at the front.